<br />Rio Blanco County Area, Colorado
<br />and the more desirable forage plants have achieved
<br />sufficient growth to withstand grazing pressure.
<br />This map unit is in capability subclass Vlle,
<br />nonirrigated. It is in Clayey Foothills range site.
<br />32-Fluvaquents, frequently flooded. This map unit
<br />is on alluvial valley floors and flood plains and in
<br />oxbows, swales, and old river channels along major
<br />rivers and streams. It formed in mixed alluvium derived
<br />dominantly from sedimentary and basaltic material. Slope
<br />is 0 to 3 percent. Areas are elongated and are 5 to 30
<br />acres. The native vegetation is mainly willows, water-
<br />tolerant grasses, and some cottonwood trees. Cattails
<br />are in some of the low-lying oxbows. Elevation is 5,100
<br />to 7,400 feet. The average annual precipitation is 8 to 20
<br />inches, the average annual air temperature is 38 to 50
<br />degrees F, and the average frost-free period is 45 to 120
<br />days.
<br />These soils are deep and poorly drained. They consist
<br />of thin layers of highly stratified clay loam to sand
<br />underlain by very gravelly and cobbly sand.
<br />Included in this unit are small areas of Redrob loam,
<br />Redrob Variant loam, Colorow sandy loam, and
<br />Trembles loam, wet.
<br />Permeability is very rapid. Available water capacity is
<br />moderate to high. The rooting depth is adequate to
<br />support only water-tolerant vegetation. A seasonal high
<br />water table fluctuates between depths of 6 and 36
<br />inches in spring and summer. Most of this unit is subject
<br />to periods of flooding in spring.
<br />Use of this unit is limited to some livestock grazing
<br />after the periods of flooding in spring and to habitat for
<br />some watertowl, muskrat, and beaver.
<br />This map unit is in capability subclass Vllw. It is in
<br />Riverbottom range site.
<br />33-Forelle loam, 3 to 8 percent slopes. This deep,
<br />well drained soil is on terraces and uplands. It farmed in
<br />eolian and alluvial material derived dominantly from
<br />sedimentary rock. Areas are irregular in shape and are
<br />20 to 600 acres in size. The native vegetation is mainly
<br />low shrubs and grasses. Elevation is 5,800 to 7,200 feet.
<br />The average annual precipitation is 15 to 18 inches, the
<br />average annual air temperature is 42 to 45 degrees F,
<br />and the average frost-free period is 80 to 105 days.
<br />Typically, the surface layer is pale brown loam 4
<br />inches thick. The upper 12 inches of the subsoil is
<br />yellowish brown clay loam, and the lower 5 inches is
<br />light yellowish brown loam. The substratum to a depth of
<br />60 inches or more is very pale brown loam.
<br />Included in this unit are small areas of Patent loam,
<br />Piceance fine sandy loam, Work loam, Yamac loam, and
<br />Zoltay clay loam. Included areas make up about 15
<br />percent of the total acreage. The percentage varies from
<br />one area to another.
<br />Permeability of this Forelle soil is moderate. Available
<br />water capacity is high. Effective rooting depth is 60
<br />35
<br />inches or more. Runoff is medium, and the hazard of
<br />water erosion is moderate.
<br />Most areas of this unit are used for nonirrigated and
<br />irrigated crops, livestock grazing, and wildlife habitat. A
<br />few areas are used for urban development and as a
<br />source of topsoil.
<br />This unit is well suited to nonirrigated small grain and
<br />irrigated hay and pasture. Wheat is the main nonirrigated
<br />crop.
<br />If this unit is used for small grain, the main limitations
<br />are the hazard of erosion, a short growing season, and
<br />low precipitation. Because precipitation is not sufficient
<br />for annual cropping, a cropping system that includes
<br />small grain and summer fallow is most suitable.
<br />Maintaining crop residue on or near the surface
<br />reduces runoff, reduces soil blowing, and helps to
<br />maintain soil filth and organic matter content. Soil
<br />blowing can also be reduced by keeping the soil rough
<br />and cloddy when it is not protected by vegetation. On
<br />long slopes, chiseling the stubble in fall slows runoff and
<br />reduces soil loss in years when the snow melts rapidly
<br />while the soil is still frozen. Chiseling also promotes
<br />better aeration.
<br />This unit is well suited to hay and pasture. The main
<br />limitations are a short growing season, the hazard of
<br />water erosion, and low precipitation. Use of nitrogen,
<br />phosphorus, and manure fertilizer promotes good growth
<br />of forage plants. Proper stocking rates, pasture rotation,
<br />and restricted grazing during wet periods help to keep
<br />the pasture in good condition and to protect the soil from
<br />erosion. Irrigation water can be applied by the sprinkler,
<br />corrugation, and controlled flooding methods. Leveling
<br />helps to insure the uniform application of water,
<br />The potential plant community on this unit is mainly
<br />western wheatgrass, prairie junegrass, big sagebrush,
<br />Douglas rabbitbrush, streambank wheatgrass, and
<br />needleandthread. The production of forage is limited by
<br />a short growing season and low precipitation. The
<br />average annual production of air-dry vegetation is about
<br />800 pounds per acre.
<br />If the range is overgrazed, the proportion of preferred
<br />forage plants decreases and the proportion of less
<br />preferred forage plants increases. Therefore, livestock
<br />grazing should be managed so that the desired balance
<br />of preferred species is maintained in the plant
<br />community.
<br />Management practices suitable for use on this unit are
<br />proper range use, deferred grazing, rotation grazing, and
<br />brush management. If the range is in poor condition,
<br />seeding is also a suitable practice where slopes are less
<br />than 15 percent. For successful seeding, prepare a
<br />seedbed and drill in the seed. The plants selected for
<br />seeding should meet the seasonal requirements of
<br />livestock or wildlife, or both.
<br />If this unit is used for urban development, the main
<br />limitations are low soil strength, the potential for
<br />shrinking and swelling, and the hazard of frost action.
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